1. Technical Field
The invention relates generally to roof coating applications. More particularly, the invention relates to an improved method and apparatus for delivering hot bituminous material from a vessel containing the material onto a roof for a subsequent application coating thereto. Even more particularly, the invention relates to such a method and apparatus which uses a pumping arrangement whereby the unused or cooled but still liquid bituminous material can be returned easily to a heated storage chamber for reheating to ensure that the material has the desired temperature and to prevent clogging of the delivery pipe and associated equipment upon cooling of the material.
2. Background Information
Various processes and apparatus have been developed for applying a heated roofing material, usually a hot bitumen, which is mopped or sprayed onto a roof for adhering of a roof covering thereon. This bitumen is usually heated in a mobile vessel located on the ground adjacent the building in which either a new roof is being applied or an existing roof is being reroofed. These vessels are referred to in the roofing industry generally as roofing kettles. One example of such a kettle is shown in pending application Ser. No. 08/768,963. These roofing kettles usually contain a storage chamber which is heated, usually with propane or natural gas heaters, which melts the hardened blocks of bitumen and maintains the resulting liquid at the desired elevated temperature. The heated bitumen is then pumped to the roof site through a conduit where it is usually deposited into a smaller mobile vessel, generally referred to in the industry as a roof lugger. In certain applications, the delivery conduit may be connected directly to a mop or spray applicator for direct application of the heated material to the roof. After the bitumen is applied to the roof, a covering which generally comes in roll form is applied and adhered thereto by the bitumen with the subsequent application of a ballast such as gravel.
One problem that always occurs in the use of such heated bitumen is that if the application of the heated roofing material is not continuous the bitumen will cool and at times harden in the delivery conduit or in the roof lugger or application tool making it an unsatisfactory roofing installation and requiring the cleaning and/or disposal of the equipment and tools in which the bitumen has hardened.
This can occur due to work stoppage on the roof for various reasons such as the unavailability of the rolls of roofing material, breaks by the working personnel or numerous other reasons causing a delay in the application of the heated roofing material. Furthermore, at the end of a work shift or roofing job, the excess material then must be returned by some manner to the ground where it hardens and then is disposed of or returned to the kettle for reuse the next day or at another job site. This becomes difficult and time consuming.
There is no known method and apparatus of which we are aware which enables the material to be delivered directly to the roof from a roofing kettle usually located at the ground, which also is provided with a pumping mechanism enabling the excess material to be returned to the heated kettle to prevent hardening of the material within the delivery pipe or roof lugger or application tool.